The logo of Dow Jones Industrial Average stock market index listed company JPMorgan Chase (JPM) is seen in Los Angeles, California, United States, in this October 12, 2010 file photo. REUTERS/Lucy Nicholson/File Photo

Despite an uptick in IPOs since June, activity remains below 2015 levels, largely due to low U.S. interest rates that have made it easy for companies to borrow cheaply and made it more attractive for them to raise funds through debt offerings.

Fees for debt issues are typically lower than those on equity offerings.

The U.S. Federal Reserve had been expected to raise interest rates four times this year, but the central bank hasn't budged.

Eight companies made their market debut this week, raising a total of $1.22 billion. Five listed one or more of the six big banks as a lead manager, according to Renaissance Capital, a manager of IPO-focused ETFs.

Just 70 companies have gone public this year through Friday, down from 122 in the same period last year - the lowest since 2009. The amount raised totaled about $11.8 billion, a drop of 52 percent, according to Thomson Reuters data.

Equity offerings in the United States fell 36 percent to $122.7 billion through the week of Sept. 16. Debt offerings were little changed at $1.7 trillion.

TOUGH YEAR

"The first half of this year has been a uniquely difficult environment for underwriting revenue on the equity side," Jeffery Harte, an analyst with Sandler O'Neill told Reuters.

Jay Ritter, an IPO expert and a professor at the University of Florida, said 2016 would be a moderate year for IPOs.

"Investment banking underwriting revenue will almost certainly decline this year," he said.

"Equity underwriting is the most profitable part of the business, but IPO volume is down and the trend for follow-on offerings to be done with bought deals rather than fully marketed bookbuilt deals is also lowering the average revenue per deal."

The Fed's target rate for overnight lending between banks is 0.25 percent to 0.50 percent, where it has been since December last year when it was raised for the first time in nearly a decade. [nS0N1AL01N]

Apart from low interest rates, U.S. investment banks have been hit by weak oil prices, Britain's vote to leave the European Union and concerns about global economic growth.

Globally, investment banks suffered their worst first-half performance since the 2008 financial crisis, with revenue for the top 12 players falling 15 percent from a year earlier, according to industry analytics firm Coalition. [nL8N1BY49V]

Even so, U.S. banks took the top five spots in global investment banking revenue during the period.

JPMorgan, the biggest U.S. bank by assets, retained its spot at the top of the global investment bank rankings despite a drop of 11.7 percent in fees from investment banking.

The bank was an underwriter for the IPO of Japanese messaging app operator Line Corp, the biggest U.S. IPO so far this year. Line's shares soared as much as 36 percent in their debut, valuing the company at $9.34 billion.

(Reporting by Sweta Singh and Ankur Banerjee in Bengaluru; Editing by Ted Kerr)